Lubricating grease

ABSTRACT

LUBRICATING GREASES COMPRISED OF A METAL SOAP AND A MAJOR AMOUNT OF MINERAL OIL ARE IMPROVED IN THEIR ANTICORROSION PROPERTIES BY INCLUDING IN THEM SYNERGISTIC MIXTURES OF A BARIUM ALKARYL SULFONATE WHEREIN THE ALKARYL GROUP HAS A MOLECULAR WEIGHT BETWEEN 330 AND 430 AND A NAPHTHENATE SALT OF ZINC, LEAD, LITHIUM OR MAGNESIUM.

United States Patent "ice Meme, 2512 31 2 The naphthenate may be a saltformed from metals of 3,684,726 Groups I to IV of the Mendeleev Periodictable. LUBRICATING GREASE A preferred form of grease in accordance withthe Alfred Romlla d Haak, 2105 Meckelfeld, Mohhweg invention maycomprise about 1.5 percent by weight of the Germany, and Wolfgangstlchnoth 15 Muhlensfl'asse naphthenate salt and about 0.5 percent byweight of the 2000 Hamburg 70, Germany sulphonate salt.

P 17 69 551 sulphonate, and the metal soap matrix of the grease may I t,(3], 010m 5/22, 5/16 be a salt of 12-hydoxystearic acid, such as thelithium salt US. Cl. 25233.2 5 Claims thereof.

In order to demonstrate the technical advance provided by the invention,a number of tests were performed in ABSTRACT OF THE DISCLOSUREaccordance with the method of DIN 51802 in which rela- Lubricatinggreases comprised of a metal soap and a rotahoh is Produced between a ag face a d a major amount of mineral oil are improved in their antil5Shaft which are Separated by Toner g the beaflngs corrosion propertiesby including in them synergistic rniX- helhg lubncatad y the greaseunder test In the Presence tures of a barium alkaryl sulfonate whereinthealkaryl of stahdardlzad q y 0f Wataf- A ter a standard group has amolecular Weight between 3 and 430 and a per1od of operation, the amountof COIIOSIOD is determined.

naphthenate salt of zinc, lead, lithium or magnesium. Each test wasPerformed w fi me with distilled water and the second time using asynthetic seawater formulated in accordance with procedure B of testASTM D 665.

The amount of corrosion was expressed on an arbitrary scale in whichzero corresponds to no corrosion of the surface of the test sample,and 5designates over 10% of the The corrosion of metal parts lubricated bygrease in hostile environments is mitigated by including 1n the grease asynergistic combination of naphthenates and sulphoft present inventionrelates to lubricating grease. A surface of the test sample corroded.Corrosion of less than lubricating grease basically compriseslubricating oil 10% of the Surface was P h a Pf raia asis. trapped i hinterstices of a n-i f Soap fib Th The results of the tests aresummarised 1n the following soap is usually a metal salt of a long chainorganic acid table:

TABLE 7 Test number 1 2 3 4 5 6 7 8 9 10 11 12 13 4 15 Grease (90 wt.percent mineral oil plus 10% lithium 12 hydroxystearate 100 99.5 99.0 980 98.0 98.0 98.0 99.5 99.0 98.0 98.5 98.0 99.0 98.0 98.0 Leadnaphthenatm. 2 0 "56 0,5 Lithmmmphthmt '"""11113111112:. .ra:::::.::"i'a"'z 's':::::: "i' lirgnm 2.0 g 0 fiiiifii lh impmarnamnesia: 0.51.0 2.0 0.5 0.5 0.5 0.5 0,5

OHOSIOD es S1 3 2 1 0 o 0 e 0 o 0 0 o o 0 0 8% $333 32125 i'ii tifi ainmgtarains-6e- 5 4 a 2 2 2 1-2 4 3 3 2 O H 0 0 and among the commonlyused soaps are the metal salts An examination of the data in the tableshows that in of 12-1 d i id, tests 2 to 10, a s ngle additive, elthenanaphthenate salt Lubricating grease often is employed in situationswhere or a sulphonate, lmproved the corroslon protection with moisturecan penetrate to the metal parts which are lubrlr spect to the greasealone in t s both W1th dlstllled cated by the grease, for example, insteam-driven turbines. water and sea-water accordmg to test DIN 51802.Greases employed in such situations may contain additives However, 1twill be seen that when a combination of which combat any tendency of themetal parts to become one or more naphthenates w th the sulphonat 1mcPrcorroded by the moisture. Commonly-used additives are porated 1n thegrease, t e ls a synerglstlc effect which metal salts of naphthenic acidor alternatively metal salts confers further corrosion protectionproperties on the of sulphonic acids. However, these additives are notcorng as C mpared W1th the amount of rotection when pletely effective inpreventing corrosion, and are relatively only one additive chem1c al isemployed. In the case of ineffective where the moisture is associatedwith inorganic tests 14 a d 15, there is complete corroslon protect onsalts, as is the case with seawater. even in the Presence er- I I It hasnow been discovered, in accordance with the in- In further tests Whlch wCarried out, this time 1n vention, that improved anti-corrosionproperties are imaccordance with ASTM D 1743, the basic gfeasa had aparted to a lubricating grease by incorporating in the COTTOSIOHpl'otectlofl 0f 011 he Scale prescnbed 1n grease an additive comprisinga combination of at least ASTM D 1743- W 2 Welght Percent of bahlumylone sulphonate salt and at least one naphthenate salt. naphthalenesulphonate was rp r ed 111 he baslc As will be seen from data givenbelow, the combination grease, the protection as d termined by ASTM D1743 a 1 2I of sulphonate and naphthenate salts act synerglstically towas provide corrosion protection of metal parts even in the hlehds waremade P 0f the bfislqgfeasa w h 2% y presence f Seawater. weight of thenaphthenates of lead, mm and lithium, and

The sulphonate salt is preferably a salt of an alkaline tested accordingto ASTM D 1743- each blend, the

earth metal from Group 11(a) of the Mendeleev Periodic corrosionPl'otection was It was found that no improvement could be obtained table(Such as banum calcium or Strontium) but Sulpho in the corrosionprotection by increasing the concentration nates of metals in Groups11(b) (such as magnesmm and of the additive in the just described tests-Zihc) y also be employed- However, when a grease blend comprising 1 wt.percent The sulphonates y he a Petroleum sulphonate an 7 of bariumdinonylnaphthalene sulphonate and 0.5 wt. peralkafyl sulphonata-Preferably, the molecular weight of cent of zinc naphthenate was tested,the corrosion protecthe hydrocarbyl group of the sulphonate is 330 to430. tion according to ASTM D 1743 was 1, thus demonstrating thesynergistic effect of combining a naphthenate and a sulphonate.

These results serve to confirm the results summarized above in thetable.

A grease giving highly satisfactory corrosion performance has been madewhich comprises about 1.5 weight percent of the naphthenate and about0.5 weight percent of the sulphonate.

The additives in accordance with the invention do not detract from thelubricating properties of the grease.

We claim:

1. A grease composition comprising mineral lubricating oil thickenedwith lithium 12-hydroxystearate and containing synergistic corrosioninhibiting proportions of at least one naphthenate salt of a metalselected from the group consisting of lead, zinc, magnesium, and lithiumand a barium salt of an alkaryl sulfonic acid wherein the alkaryl grouphas a molecular weight between 330 and 430.

2. A lubricating grease claimed in claim 1 wherein the naphthenate saltis zinc naphthenate.

3. A lubricating grease as claimed in claim 1 wherein the naphthenatesalt is lead naphthenate.

References Cited UNITED STATES PATENTS 8/1953 Matthews et a1. 252-33.22/1970 Haak et a1. 25233 OTHER REFERENCES Polar-Type Rust Inhibitors byBaker et al. in Industrial and Engineering Chemistry, vol. 40, No. 12,pp. 2338-2347.

DANIEL E. WYMAN, Primary Examiner I. VAUGHN, Assistant Examiner US. Cl.X.R. 25237.7, 389

